USC might be a popular pick to make the College Football Playoff, but that does not mean the Trojans are issue-free as training camp opens Saturday.

In order to satisfy the expectations of the fans and oddsmakers, some key positions must improve for USC to be a legitimate national championship contender. Here are the five most-pressing problems facing the Trojans:

1. Will the wide receivers emerge?

USC has one go-to wide receiver, Rose Bowl star Deontay Burnett. And even he was not considered a big-time receiver before the Rose Bowl, when he caught 13 passes, including three touchdowns.

Senior Steven Mitchell returns from knee surgery, sophomore Michael Pittman is tall and full of promise and then there is a group of unproven redshirt freshmen (Tyler Vaughns, Velus Jones, Josh Imatorbhebhe, Trevon Sidney) who have yet to wow anyone with their practice performances. Not to mention a couple even more unproven true freshmen (Joseph Lewis, Randal Grimes).

2. Can USC find another nose tackle?

The Trojans lucked out last season when Utah’s Stevie Tu’ikolovatu transferred in and eventually earned Rose Bowl defensive most valuable player honors. So who replaces him? The early answer is true freshman Marlon Tuipulotu, who was impressive during spring practice, when he shared time with Josh Fatu.

Two more freshmen arrived in the summer: Brandon Pili and Jay Tufele.

But the wild card is Kenny Bigelow, who has played in just 13 college games the past four seasons after two major knee operations. Bigelow is supposed to be healthy and his experience would be vital at a youthful position.

3. Will the offensive tackles be dependable?

You can make the case that quarterback Sam Darnold’s mobility and poise mean an average offensive lineman is good enough to protect him. But can the Trojans be a national-title contender without excellent tackle play?

The left tackle is expected to be Chuma Edoga, most famous last season for shoving a referee and being ejected from a game. Edoga said he matured from last year. If he struggles, USC might turn to the versatile Toa Lobendahn, who can play every line position.

Lobendahn will probably open the season at offensive guard. Or maybe even right tackle, which is also a big question mark. Chris Brown looked like the likely starter at the end of spring practice but nothing was finalized.

Don’t be surprised if true freshman Austin Jackson gets a lot of practice time in training camp because he is considered an offensive tackle of the future. Either way, there is uncertainty at a key position providing protection for Darnold.

4. Can anyone replace Adoree’ Jackson?

USC has a big void at cornerback. Even though Jackson gave up more big plays than it would seem with his reputation, there is no one on the roster with his instincts or athleticism.

Iman Marshall is the No. 1 cornerback and sophomore Jack Jones is expected to start despite an inconsistent first season. Ajene Harris ended last season as the nickel back. It’s wide open after that, although Jonathan Lockett started five games before he was injured.

There is also the question whether anyone can replace Jackson on special teams, where he returned eight punts and kickoffs for touchdowns in three seasons.

Speaking of special teams, freshman kicker Michael Brown must replace Rose Bowl hero Matt Boermeester, who was removed from the program after an incident with a female student.

5. Who is the backup quarterback?

Matt Fink redshirted and will serve as the official backup. In a perfect season, Fink gets mop-up duty in several games after Darnold compiles some Heisman Trophy-worthy stats. USC would like to redshirt incoming freshman Jack Sears.

However, what happens if Darnold gets injured? The coaches view Sears as a long-term answer and he would need to play if Darnold were out for an extended period. The challenge is how long will it take Sears to learn the offense?

Don’t rule out the idea of wide receiver Jalen Greene being an emergency quarterback if Darnold were sidelined for only a game or two.